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Full text of "Residual kaolin deposits of the spruce pine district, North Carolina"

North Carolina State ttbraJK N.Ob 

t'ljLf Raleigh DOC 

c 2 NORTH CAROLINA 

DEPARTMENT OF CONSERVATION AND DEVELOPMENT 






R. BRUCE ETHERIDGE, DIRECTOR 



DIVISION OF MINERAL RESOURCES 

JASPER L. STUCKEY, STATE GEOLOGIST 



Bulletin Number 48 



RESIDUAL KAOLIN DEPOSITS OF THE 

SPRUCE PINE DISTRICT, 

NORTH CAROLINA 



BY 
JOHN M. PARKER III 



prepared by geological survey, u. s. department of the interior 

in cooperation with the 
North Carolina department of conservation and development 

RALEIGH 
1946 



NORTH CAROLINA 
DEPARTMENT OF CONSERVATION AND DEVELOPMENT 

R. BRUCE ETHERIDGE, DIRECTOR 



DIVISION OF MINERAL RESOURCES 

JASPER L. STUCKEY, STATE GEOLOGIST 



Bulletin Number 48 



RESIDUAL KAOLIN DEPOSITS OF THE 

SPRUCE PINE DISTRICT, 

NORTH CAROLINA 



BY 
JOHN M. PARKER III 



prepared by geological survey, u. s. department of the interior 

in cooperation with the 
North Carolina department of conservation and development 

RALEIGH 
1946 



MEMBERS OF THE BOARD OF CONSERVATION 
AND DEVELOPMENT 

Governor R. Gregg Cherry, Chairman _. Raleigh 

J. L. HORNE, Vice Chairman Rocky Mount 

Charles S. Allen Durham 

Oscar P. Breece Fayetteville 

J. Wilbur Bunn Raleigh 

K. Clyde Council Wananish 

R. Floyd Grouse Sparta 

W. J. Damtopt Canton 

Percy B. Ferebee Andrews 

A. H. GuiON Charlotte 

W. Roy Hampton- - Plymouth 

R. W. Proctor Marion 

Miles J. Smith Salisbury 

D. M. Stafford Pomona 

A. K. Winget Albemarle 

J. R. Wollett Littleton 



CONTENTS 

Page 

Letter of transmittal 5 

Preface 6 

Abstract 7 

Introduction 8 

Purpose of investigation 8 

Summary of previous work 8 

Limits and methods of investigation 9 

Acknowledgments 10 

Geography of district 11 

Location 11 

Transportation 1 1 

Topography r 1 1 

Geology of district 13 

Formations 13 

Metamorphic rocks 13 

Mica gneiss 13 

Mica schist 13 

Hornblende gneiss 13 

Injection gneiss 14 

Igneous rocks , 14 

Ultrabasic intrusives 14 

Granite 14 

Pegmatite 1 5 

Structure 16 

Kaolin deposits 17 

History and production 17 

Geologic situation and origin 20 

Rock types 20 

Fractures 20 

Inclusions 2 1 

Overburden 21 

Topographic situation 22 

Composition 23 

Mining and processing 25 

Reserves 26 

Totals for the district 26 

Appraisal of data 26 

Areas 26 

Thicknesses 27 

Inclusions 27 

Densities 27 

Recoveries 28 



CONTENTS — Con. 

Page 

Kaolin deposits — Continued. 

Distribution and grouping 28 

Individual deposits and groups 28 

Brushy Creek group 28 

Gusher Knob group 32 

Spruce Pine group 34 

Spruce Pine deposit 35 

Grassy Creek deposits 35 

English Creek deposits ,. 37 

Bear Creek deposits 37 

Miscellaneous deposits 37 

Newdale-Lunday group 38 

Newdale deposits 38 

Butler Gap deposits 38 

Boonford deposit 40 

Lunday deposits „_ 40 

Miscellaneous deposits : 41 

Summary and conclusions 42 

Appendix A 43 

ILLUSTRATIONS 

FIGURES 

Figure 1. Plant of Kaolin, Inc., near Spruce Pine, N. C 19 

2. Mine of Kaolin, Inc., near Spruce Pine, N. C 29 

3. Mine of Harris Clay Company near Lunday, N. C. 40 

PLATES 

Plate 1. Map of the Spruce Pine district, North 
Carolina, showing locations of kaolin 
deposits . In Pocket 

2. Map of the Gusher Knob-Brushy Creek 
district, North Carolina, showing granite 

bodies and kaolin deposits In Pocket 

3. Geologic map of the Brushy Creek kaolin 

deposits, Avery county, North Carolina In Pocket 

4. Map of the Spruce Pine-Micaville district, 
North Carolina, showing granite bodies 

and kaolin deposits In Pocket 



LETTER OF TRANSMITTAL 



Raleigh, North Carolina 
February 12, 1946 



To His Excellency, Hon. R. Gregg Cherry, 
Governor of North Carolina. 

Sir : - 

I have the honor to submit herewith, manuscript for publi- 
cation as Bulletin 48, "Residual Kaolin Deposits of the Spruce 
Pine District, North Carolina," by J. M. Parker, III. 

North Carolina has been, for a number of years, the leading 
producer of residual kaolin in the United States. This report 
has been prepared with special reference to the reserves of 
kaolin available in the area covered. The data available in this 
report, when used in connection with information available in 
previous publications of this Department, should be of great 
value to the kaolin producers and potential ceramic industry of 
the State. 

Respectfully submitted, 

R. Bruce Etheridge, 
Director. 



PREFACE 

i 

Three previous reports relating to the kaolin deposits of the 
State have been published by the North Carolina Geological and 
Economic Survey, predecessor to the North Carolina Depart- 
ment of Conservation and Development : 

(1) Bulletin 13, "Clay Deposits and Clay Industry in 

North Carolina," pp. 50-70, 1897, 
by H. Ries. 

(2) Economic Paper 34, "Feldspar and Kaolin De- 

posits," pp. 185-289, 1914, by A. S. 

Watts. 

(3) Bulletin 29, "The Kaolins of North Carolina," 

1925, by W. S. Bayley. 

These reports were prepared for the purpose of giving informa- 
tion on both the geology and uses of North Carolina kaolins. 

The present report has been prepared in cooperation with the 
United States Geological Survey, by Dr. J. M. Parker, III, of that 
organization. The field work on which this report is based was 
done in the spring of 1942, at a time when the possibilities of 
producing aluminum from white clays were of tremendous im- 
portance due to war conditions. As a result, this report deals 
with the kaolin reserves of the Spruce Pine district of North 
Carolina with special reference to the occurrence of kaolin and its 
possible use in the production of aluminum. 

Any possible need of aluminum from kaolin was removed by 
the successful termination of World War II. The information 
contained in this report, however, is too valuable to lose, particu- 
larly that dealing with the geological setting and the reserves of 
kaolin in the State. North Carolina kaolins have had a wide use 
for many years in making china, semi-porcelain and porcelain, 
mosaic and other tile, and in the manufacture of spark plugs and 
glass melting pots. A new use is its employment as a raw 
material in making spun glass. Recent improvements in the 
refining of kaolin assure to the trade ample supplies of blended 
kaolin of uniform quality which is equal to the best imported 
kaolin. 

It is believed that the information contained in the present 
report, when studied in connection with Bulletins 40 and 44, of 
this Department, and entitled respectively "Manufacturing China 
Clay Opportunities in North Carolina," and "Economic Oppor- 
tunities for Producing Semi-Porcelain Dinnerware in North 
Carolina," will be of great value to the kaolin and potential 
ceramic industry of the State. 

Jasper L. Stuckey, 
State Geologist. 



RESIDUAL KAOLIN DEPOSITS OF THE SPRUCE 
PINE DISTRICT, NORTH CAROLINA 

By John M. Parker III 



ABSTRACT 



The residual kaolin deposits of the Spruce Pine district in 
Avery, Mitchell and Yancey counties, North Carolina, were ex- 
amined to determine their suitability for aluminum ore. These 
deposits lie midway between the aluminum reduction plants at 
Alcoa, Tennessee, and at Badin, North Carolina, about 175 miles 
by railroad from each. They are readily accessible, lying near 
the railroad or good highways. The principal deposits were 
formed by chemical weathering of small irregular stocks of 
granite, which were intruded during the late Paleozoic into 
steeply dipping pre-Cambrian gneisses and schists. They are 
composed of kaolin mixed with partly decomposed oligoclase and 
microcline, unaltered quartz and muscovite. Ferromagnesian 
minerals are practically absent except for occasional spots of iron 
and manganese oxide resulting from the decay of garnets. All 
the known deposits occur where the granite bodies underlie the 
strath of the North and South Toe Rivers and their tributaries. 
Prolonged decomposition during an earlier, incomplete erosion 
cycle, rather than under present circumstances, appears to have 
been responsible for the kaolinization. In favorable locations 
the decomposition has extended downward as much as a hundred 
feet but most of the deposits can not be worked deeper than 40 
or 50 feet. Deposits in the lower and central parts of the strath 
are usually capped with stream sediment from 1 to 30 feet thick, 
while marginal deposits have an overburden of 3 to 10 feet 
of stained residual soil. The deposits are interrupted by many 
small and large inclusions of country rock. Inclusions and walls 
of hornblende gneiss are especially detrimental, as serious iron 
oxide stain is usual near them. The washed kaolin produced 
from these deposits runs 37 percent or more in alumina and 
under one percent in ferric oxide. Because of the uniformity 
of the deposits special emphasis was placed on obtaining as exact 
and reliable estimates as possible of the amount available. The 
Brushy Creek deposits were estimated to contain between li/o 
and 3 million tons of washed kaolin, the Gusher Knob deposits 
between 450,000 and 1,250,000 tons, the Spruce Pine group 



8 Residual Kaolin Deposits of the 

between 700,000 and 1,600,000 tons, and the Newdale-Lunday 
group between 400,000 and 1,300,000 tons; the total for the 
district is between 3 and 7 million tons. On the basis of quality, 
size and accessibility the first three groups are considered poten- 
tial sources of aluminum ore; the fourth is submarginal in this 
respect. 

INTRODUCTION 

PURPOSE OF INVESTIGATION 

The purpose of the present investigation was to appraise the 
clay resources of North Carolina as possible aluminum ores. 
Recent research and pilot-plant experimentation have developed 
technologic methods of extracting aluminum from silicates, 
especially high-alumina clays, on a large scale. The tremen- 
dously expanded use of aluminum in defense and war production 
has drained heavily on the known bauxite deposits in the United 
States, while the acute shipping shortage has limited importa- 
tion of foreign bauxite. In order to alleviate this threatened 
shortage and to develop, if possible, adequate sources of alumi- 
num ore within the United States, an expanded program by the 
Geological Survey and the Bureau of Mines, United States De- 
partment of the Interior, was set up by special Congressional 
appropriation to study bauxite, alunite, and high-alumina clays. 
This report results from an investigation by the U. S. Geological 
Survey of the residual kaolins of western North Carolina as a 
part of this larger program. The study was directed especially 
toward obtaining specific and reliable estimates of the tonnage 
available. 

SUMMARY OF PREVIOUS WORK 

A survey of the geologic literature indicated that the only 
clays in North Carolina of a suitable quality for aluminum ore 
and in sufficient quantity to be of importance were the residual 
kaolins in the mountain sections, especially those in Avery, 
Mitchell and Yancey counties. These deposits have been de- 
scribed by Ries 1 2 3 , Watts 4 , Bayley 5 , Hunter and Mattocks 6 , and 

1 Ries, Henrich, Clay deposits and clay industry in North Carolina : North Carolina Geol. 
Survey Bull. 13, pp. 50-70, 1897. 

2 Ries Heinrich, The clays of the United States east of the Mississippi River : U. S. Geol. 
Survey Prof. Paper 11, 298 pp., 1903. 

3 Ries, Heinrich, Baylev, W. S., and others, High grade clays of the eastern United States: 
U. S. Geol. Survey Bull. 708, pp. 18-79, 1922. 

* Watts, A. S. Mining and treatment of feldspar and kaolin : U. S. Bur. Mines Bull. 53, 
170 pp., 1913. 

5 Bayley, W. S., The Kaolins of North Carolina : North Carolina Geol. and Econ. Survev 
Bull. 29, 132 pp., 1925. 

6 Hunter, C. E., and Mattocks, P. W., Geology and kaolin deposits of Spruce Pine and 
Linville Falls quadrangles, North Carolina : Tennessee Valley Authority, Division of Geology 
Bull. 4, pt. 1, pp. 10-23, 1936. 



Spruce Pine District, North Carolina 9 

Hunter 7 . Publications on related subjects in the same area in- 
clude those of Keith 8 , Sterrett 9 , Maurice 10 , Kesler and Olson 11 , 
and Olson 12 . F. L. Hess of the Bureau of Mines prospected part 
of the Gusher Knob deposits but the results were not published. 
Detailed descriptions of many mines and prospects, and of the 
general occurrence and origin of the clay, have thus long been 
available, but estimates of reserves in the district have been 
lacking or very rough. The most specific is that of Hunter 13 , 
giving fifty one million tons of crude kaolin in Avery, Mitchell, 
and Yancey counties. His estimates for the individual deposits 
were not published but have been communicated personally. 
They served as a guide to the most promising localities. 

LIMITS AND METHODS OF INVESTIGATION 

Only the larger and more accessible occurrences of kaolin in 
the district were studied. To constitute a practicable source of 
aluminum ore, a clay deposit had to meet the following specifi- 
cations, established by the Bureau of Mines : 

1. The deposit must be located within 150 miles of an existing 
aluminum reduction plant. 

2. The deposit must contain at least one million tons of clay. 

3. The clay must be at least 15 feet thick. 

4. The clay must run over 35 percent A1 2 3 and under IV2 
percent of Fe 2 3 . 

5. The overburden must not be thicker than the clay. 

The deposits in the Spruce Pine district which gave any promise 
of meeting these requirements were studied in considerable de- 
tail. Preliminary work indicated that only two localities were 
likely to be large enough in themselves, but that a number of 
smaller deposits fairly close to each other might as a group ful- 
fill the necessary conditions. Consequently the field work was 
concentrated on four groups of deposits, two closely spaced ones 
(Brushy Creek and Gusher Knob) where the productive areas 
were only a few hundred feet from each other, and two dispersed 
groups (Spruce Pine and Newdale-Lunday) with the units a 
few miles apart. 



7 Hunter, C. E., Residual alaskite kaolin deposits of North Carolina: Am. Ceramic Soc. 
Bull., vol. 19, no. 3, pp. 98-103, March, 1940. 

8 Keith, Arthur, U. S. Geol. Survey, Geol. Atlas, Mount Mitchell folio (no. 124), 10 pp., 1905. 

9 Sterrett, D. B., Mica deposits of the United States: U. S. Geol. Survev Bull. 740, 342 pp., 
1923. . m» . 

10 Maurice, C. S., The pegmatites of the Spruce Pine district. North Carolina: Econ. Geologv, 
vol. 35, nos. 1 and 2, pp. 49-78 and 158-187, 1940. 

11 Kesler, T. L., and Olson, J. C, Muscovite in the Spruce Pine district, North Carolina: 
U. S. Geol. Survey Bull. 936-A, 38 pp., 1942. 

12 Olsen, J. C, Economic Geology of the Spruce Pine pegmatite district, North Carolina : 
North Carolina Dept., Cons, and Devel. Bull. 43, pt. 1, 1944, pt. 2, 1945 

13 Hunter, C. E., op. cit., p 102. 



10 Residual Kaolin Deposits pf the 

The field work occupied nearly four months between February 
18 and June 11, 1942. It started with detailed areal mapping to 
outline the areas underlain by granite, from which the kaolin has 
been formed by chemical weathering. For much of the Spruce 
Pine quadrangle this had already been done, during recent 
(1939-1941) study of the pegmatites by the U. S. Geological 
Survey and the North Carolina Department of Conservation and 
Development 15 . Concurrently data were collected concerning 
where and to what depths the granite was sufficiently decom- 
posed to yield kaolin in commercially important amounts. These 
data were obtained by observing exposures along streams, roads, 
railroads, and elsewhere, by noting the character of the soils, and 
by examining hundreds of prospect holes, open pits, mine shafts 
and adits. In wooded areas, boring with a soil auger gave 
valuable information not otherwise obtainable. Active kaolin 
pits and worked-out mines were studied to learn what geologic 
and topographic factors favored exploitable deposits. This ex- 
perience aided in making reasonable estimates where more 
reliable data could not be secured. 

ACKNOWLEDGMENTS 

The investigation was carried out under the supervision of 
Dr. G. R. Mansfield, at that time Geologist in charge, Section of 
Areal and Nonmetalliferous Geology, U. S. Geological Survey. 
The manuscript was reviewed by Dr. H. M. Bannerman and Dr. 
V. T. Allen. Dr. J. L. Stuckey, State Geologist of North Caro- 
lina, gave valued suggestions concerning both the field work and 
the report. Mr. F. E. Smith, manager of the Harris Clay Com- 
pany, cooperated throughout the study with information about 
particular deposits and the district as a whole. Mr. W. B. 
Deneen, manager of the Carolina China Clay Company, supplied 
information about the Bear Creek deposits especially. Mr. 
Richard Janatka, superintendent at Kaolin, Incorporated, fur- 
nished logs of borings and a map of the Brushy Creek area, and 
allowed the use of laboratory equipment in making density 
determinations. Mr. C. E. Hunter and Mr. H. S. Rankin of the 
Regional Products Research Division, Commerce Department, 
Tennessee Valley Authority, contributed details of the former's 
clay investigation in the district. Mr. F. L. Hess of the U. S. 
Bureau of Mines allowed the use of the available records of his 
prespecting of the Gusher Knob deposits. Many residents of the 
district aided with information of various sorts. 



15 Olson, J. C, op. cit. 



Spruce Pine District, North Carolina 11 

GEOGRAPHY OF DISTRICT 

LOCATION 

The kaolin deposits investigated lie in what is referred to as 
the Spruce Pine district, the most important center of mica, 
feldspar, and kaolin production in North Carolina. The de- 
posits are scattered over an area extending about sixteen miles 
east-west and eight miles north-south, in parts of Avery, Mit- 
chell, and Yancey counties. The area lies in the Linville Falls, 
Spruce Pine, and Micaville 7I/2' quadrangles, nearly midway of 
the State in a north-south direction and near its western border. 

TRANSPORTATION 

The Carolina, Clinchfield and Ohio Railroad runs across the 
middle of the district following the valley of the North Toe 
River. A spur line, the Black Mountain Railroad, runs from 
Kona to Micaville, Burnsville, and Bowditch. The Clinchfield 
connects with the Southern Railway System at Johnson City,. 
Tennessee, and at Marion, North Carolina. 

Good paved roads traverse the area. U. S. Highway No. 19-E 
runs through Spruce Pine westward and southwestward to 
Asheville, and northeastward to eastern Tennessee and western 
Virginia. North Carolina Highway No. 26 connects southward 
with the main east-west route at Marion. Many other well- 
graded dirt and gravel roads give easy access to most parts of 
the area. All important kaolin deposits are near good, mostly 
paved, roads. 

TOPOGRAPHY 

The Spruce Pine district lies in the Blue Ridge physiographic 
province, near its southeast boundary and just west of the main 
divide. The drainage is to the northwest by the North and 
South Toe Rivers, upper tributaries of the Tennessee River 
system. The topography is subdued-mountainous, with ridges 
and valleys of very irregular shape and distribution. Summits 
are rounded or flat, slopes * steep, and valley bottoms usually 
narrow. Elevations range from 2,245 feet on the North Toe 
River at the north edge of the Micaville quadrangle (pi. 4) to 
5,307 on Big Bald or Yellow Mountain; local relief is commonly 
a thousand feet. 

A well-developed strath or old erosion level is represented by 
areas of wide, flat valley bottoms, by sediment-capped terraces, 
and adjacent gently rolling country along the North Toe River 



12 Residual Kaolin Deposits qf the 

and its larger tributaries. Its altitude is 2,500-2,700 feet in the 
Micaville quadrangle, but it gradually rises upstream to 2,600- 
2,800 feet in the Spruce Pine and 2,750-2,950 feet in the Linville 
Falls quadrangle. Small tributaries like Threemile Creek (pi. 2) 
and English Creek (pi. 4) flow at the strath level, as do the upper 
portions of larger tributaries like Bear Creek and even a part of 
the upper North Toe River in Avery county. Farther down- 
stream in the Micaville quadrangle all but the smallest streams 
have incised the strath, the North Toe and South Toe Rivers 
having cut gorges 200 to 300 feet into the strath terrace. 

The strath is far from flat-topped everywhere; in most places 
it has a relief of 100 or even 200 feet. This, however, contrasts 
with the ruggedness of surrounding areas. The upper boun- 
daries usually merge by gradually steepening slopes into the 
ridge or mountain sides and are consequently ill-defined. The 
lower boundaries are often sharp where the steep sides of the 
entrenched valleys intersect the strath, but where ingrown 
meanders have formed gradual slip-off slopes, the land may de- 
scend evenly to river level. In some places the strath can be 
seen to include two or more terrace levels. In the Brushy Creek 
area three levels are clear, (1) the present floodplain of the 
North Toe River at an altitude of about 2,625 feet, (2) a wide 
flat sediment-covered terrace of about 70 acres extent at 2,700 to 
2,740 feet, and (3) narrow flat-topped ridges without sediment 
cap at 2,800 to 2,850 feet. Near Spruce Pine, however, the 
situation is less clear. Here a terrace near 2,700 feet is evident 
but with perhaps three others between 2,600 and 2,800 feet. 
Near Gusher Knob one terrace lies about 100 feet above the flat 
bottom of Threemile Creek, which is not incised. The lower and 
central portions of the strath, where not dissected by recent 
erosion, are blanketed by river sediment, presumably the rem- 
nants of floodplain deposits. The^e portions tend to be fairly 
flat and to slope gently toward the larger streams. These flat 
areas are trenched by recent gullies and small valleys. The 
upper marginal portions of the strath have little or no blanket 
of sediment. 

The physiographic history of the district has not been worked 
out in detail, but the strath is presumably of the same age as 
that described around Asheville. 



Spruce Pine District, North Carolina 13 

GEOLOGY OF DISTRICT 

FORMATIONS 

Most of the Spruce Pine district is underlain by pre-Cambrian 
sedimentary and igneous rocks which have been profoundly 
altered by regional (dynamic) metamorphism. They were later 
intruded and further modified by late Paleozoic silicic igneous 
stocks, dikes and sills. 

Nearly all of the Spruce Pine area is shown on the geologic 
map of the Mt. Mitchell quadrangle (Folio 124) but on this map 
all of the rock types described in the present report are included 
in two formations. 

METAMORPHIC ROCKS 

The older metamorphic rocks include principally mica gneiss, 
mica schist, and hornblende gneiss. These are generally con- 
ceded to be pre-Cambrian in age. Their relative ages are not 
certain though the hornblende gneiss is probably younger than 
the others. 

Mica gneiss. — The mica gneiss is a moderately fine- and even- 
grained rock containing both muscovite and biotite with quartz 
and feldspar. Small red garnets are common in many places, 
and in a few localities kyanite needles are abundant. The band- 
ing is regular and even, small bands showing great persistence 
longitudinally. Two dolomitic marble layers included in this 
series indicate a sedimentary origin for at least a part of it. 

Mica schist*. — The mica schist consists mainly of fairly coarse 
flakes of muscovite, with minor amounts of biotite, quartz and a 
little feldspar. Red garnets from 0.1 to 0.5 inch in diameter are 
abundant, and some bands, especially in the Micaville quadrangle, 
contain much kyanite. 

Hornblende gneiss. — Hornblende gneiss is interbanded with 
both of these rocks ; sometimes in layers only a few inches across 
and sometimes as a great series hundreds of feet thick. This 
gneiss usually consists of small black hornblende needles oriented 
in planes (with linear orientation in these planes less common), 
and separated by bands of quartz and feldspar. Garnets are 
rarely found. In places the rock is a coarse hornblende amphi- 
bolite almost without other minerals. Alteration has developed 
some zones with much biotite or chlorite. The mineralogical and 
chemical composition, together with the form and relations of 
the hornblende gneiss, suggest that it originated from femic 
volcanics and intrusive sills. 



14 Residual Kaolin Deposits of the 

Injection gneiss. — In some places near the granite intrusions 
(see below) mica schist and perhaps also mica gneiss and horn- 
blende gneiss have been injected and permeated on a large scale 
by granitic material, forming a distinctive rock partly of meta- 
morphic and partly of igneous origin. The addition of much 
magmatic material was accompanied by recrystallization and 
coarsening of the original constituents. This injection gneiss is 
characterized by coarse silvery muscovite leaves separated by 
lenses of quartz and feldspar. On surfaces parallel to the 
foliation the rock looks like a mica schist, but on cross breaks the 
dominance of quartz and feldspar is apparent, with the mica 
enclosing fat pods of igneous material. Veins of quartz and 
stringers of pegmatite abound. Injection proceeded so far near 
some intrusions as to separate the mica folia into shreds isolated 
in quartz and feldspar, so that the gneiss may grade into normal 
mica-bearing granite. With distance from the intrusion the 
amount of injected material may be so small that the typically 
lumpy foliation surfaces are not developed, and the rock grades 
into normal schist or gneiss. 

IGNEOUS ROCKS 

Two periods of igneous intrusion have affected the area. The 
earlier intrusions were ultrabasic, and probably pre-Cambrian 
in age. The later ones were highly silicic; analysis of their 
radioactive minerals has indicated a late Paleozoic age. 

Ultrabasic intrusives. — The earlier intrusives include dunite 
and pyroxenite, and have in part been altered to soapstone and 
talc schist. The dunites have been described recently by 
Hunter 16 . 

Granite. — All the previously mentioned formations have been 
intruded by granite. These igneous bodies appear to be irregular 
stocks (pis. 2, 4), but the depth of exposure is insufficient to 
determine whether or not they are floored. The stocks crop out 
over areas of very irregular shape and from a few hundred yards 
to one or even two miles across. With these bodies are many 
smaller steeply dipping sill-like masses, dikes, and stringers. All 
were included by Keith 17 with mica gneiss and schist in the 
Carolina gneiss formation. Watts 18 seems to have been the first 
to recognize this rock as distinctly different from others in the 



16 Hunter, C. E., Forsterite olivine deposits of North Carolina and Georgia: North Carolina 
Dept. Cons, and Devel. Bull. 41, 117 pp., 1941. 

"Keith Arthur, U. S. Geol. Survey Geol. Atlas, Mount Mitchell folio (no. 124), p. 2-3, 1905. 
18 Watts, A. S., op. cit., p. 106. 



Spruce Pine District, North Carolina 15 

area. He correctly described it as granite, composed of feldspar, 
quartz and mica only, and generally occurring as sills. Never- 
theless, by many this rock was subsequently regarded as being the 
same as the pegmatite. F. L. Hess and Hunter 19 introduced the 
use of "alaskite" for this granite because of its lack of black 
minerals, but the name is not retained here because the dominent 
feldspar does not correspond to that of the type rock to which 
the term was originally applied. This rock was also called 
alaskite by Olson 20 but he noted that the composition was not 
"strictly in accord with published analyses of alaskite," and his 
terminology is not followed in this report. 

The granite is coarse-textured, grains averaging about half an 
inch in width. Its uniformity and simplicity of composition are 
notable. In general oligoclase constitutes nearly half of the rock, 
microcline and quartz each about a quarter, and a small amount 
of muscovite the remainder. Iron-manganese garnets are quite 
abundant in places but are not usual. Biotite is rare. No other 
iron-bearing minerals are found, so the kaolin derived from the 
granite is usually entirely free of iron stain. Hunter 21 gives the 
following chemical analyses, furnished by Minpro Laboratory, 
Tennessee Mineral Products Corporation, Spruce Pine, North 
Carolina : 

Analyses of Spruce Pine Granite ("Alaskite") 

No. 1 No. 2 

(%) (%) 

Si0 2 73.96 74.30 

A1 2 3 15.77 15.50 

Fe 2 3 0.33 0.30 

CaO 1.30 0.90 

K 2 3.74 4.56 

Na 2 4.57 4.15 

Ignition loss 0.31 0.26 

Total 99.98 99.97 

Pegmatite. — Many hundreds of pegmatite dikes, lenses, and 
irregular elongate masses transect all the rocks of the district. 
In width they range from less than an inch to a hundred or more 
feet; in length from a few feet to perhaps a mile. They are 
found within the granite bodies, especially near their margins, 
as well as in the gneisses and schists. In the latter they conform 
in general to the foliation but in places cut across, and have sharp 



19 Hunter, C. E., op. cit., (1940) p. 98. 

20 Olson, J. C, op. cit., p. 22. 
^Hunter, C. E., op. cit., (1940). p. 100. 



16 Residual Kaolin Deposits jof the 

contacts. Pegmatite in the granite usually occurs as irregular 
streaks and lenses with indistinct walls grading into the granite. 
The pegmatite is distinguished from the granite by its much 
coarser texture, more variable composition and unusual minerals. 
Like the granite, the pegmatite also consists mainly of plagio- 
clase feldspar (oligoclase), microcline, quartz, and muscovite, 
but in addition often contains biotite, garnet, apatite, beryl, 
tourmaline, thulite, allanite, columbite, samarskite, uraninite, 
and others. It contrasts with granite in often having a higher 
proportion of microcline. Thus, since plagioclase weathers more 
quickly and thoroughly than microcline, the pegmatitic portions 
may yield less clay and more hard feldspar. 



STRUCTURE 

The various gneisses and schists of the district are complexly 
interbanded and succeed one another apparently without syste- 
matic repetition. Bands of one variety range from a few feet up 
to half a mile in width, and in places taper rapidly along their 
strike. One variety fingers out into another along the strike and 
parallel sections only a few hundred yards apart match very 
poorly. The regional strike is northeast; the dips are mostly 
steep to the southeast. 

The regional northeast trend has been greatly disturbed near 
the granite intrusions, so that diverse strikes and dips are found. 
Since most of the intruded rocks were foliated and steeply dip- 
ping, the granite contacts in general are concordant, but many 
detailed exposures show cross-cutting relations. Those contacts 
which parallel the regional strike tend to be simple curves, 
whereas those which run across the strike are "saw-toothed" 
with projecting dikes and sills. 

A vast number of inclusions of the earlier rocks, especially of 
injected gneiss, are found in the granite. These range in thick- 
ness from a few inches or feet up to 2,000 feet. They are very 
irregular and angular in shape but tend to be slab-like because 
of their foliation. The slabs usually stand steeply on edge, in 
positions about parallel to the foliation of the nearest wall, but 
diverse positions are also found. Some have been complexly 
crumpled and most are well impregnated with igneous material 
and cut by veins and dikes. The majority of the inclusions were 
doubtless detached from the walls but some are probably the 
remnants of roof pendants. The large number of inclusions, 
their angular shapes and sharp contacts (showing only moderate 
recrystallization and no assimilation), all suggest that erosion 



Spruce Pine District, North Carolina 17 

has barely unroofed the granite stocks. The fact that the 
granite is exposed mostly at low altitudes and rarely on the 
highest ridges supports this inference. The tremendous number 
of pegmatite dikes and quartz veins in the areas between the 
granite bodies further suggests that much of the district is under- 
lain at depth by granite. 

Faulting is indicated by slickensided fracture surfaces coated 
with manganese oxide. The impossibility of identifying and 
matching key beds leaves the displacements unknown in most 
localities, but they appear to be minor. Faults are fairly 
numerous in all types of rocks. 

Regular tectonic joint systems are rare but locally occur, 
mainly in hornblende gneiss. Irregular fractures and expansion 
joints parallel to the local land surface are common, especially in 
the granite. 

KAOLIN DEPOSITS 
HISTORY AND PRODUCTION 

Kaolin from western North Carolina is reported by Kerr-- 
to have been mined by the Indians and exported to England 
during the early part of the 17th Century. In 1767-1768 Josiah 
Wedgewood sent T. Griffiths from England to Ayoree Mt. near 
Co wee Town on the Tennessee River (apparently the Iotla Bridge 
section about 5 miles northwest of Franklin, in Macon county ) 
to obtain white clay. Griffiths cleared out an old pit from which 
clay had been taken "long before" 23 and "loaded five wagons with 
five tons of clay," which after much difficulty was shipped from 
Charleston, South Carolina, to England. At the time of Kerr's 
report (1880), no clay was being mined though its value was 
recognized. 

Modern kaolin mining started in the southwestern part of the 
State near Webster, in Jackson county, about 1888. The deposits 
in this section, derived from pegmatite dikes rather than large 
granite bodies, were small, though many were very rich. Some 
portions are said to have been so nearly pure kaolin that the 
material was sold without washing. For many years Jackson, 
Macon, and Swain counties supplied almost all of North Caro- 
lina's production but these deposits are now practically exhausted 
and have not been mined for about twenty years. 



— Kerr, W. C, The mica veins of North Carolina : Am. Inst. Min. Eng. Trans., vol. 8, p 462 
1880. 

23 Griffiths, T., Through South Carolina for clay in 1767, being the narrative of an English 
gentleman, T. Griffiths, who made this journey, mining the first kaolin in America : Ceramic 
Age, vol. 14, no. 5, pp. 165-169, November 1929. 



18 Residual Kaolin Deposits of the 

The earliest mines opened in the Spruce Pine district evidently 
were those along upper Bear Creek, worked about 1904. No 
operations in the district are mentioned by Keith 24 in 1897-1901, 
or by Ries 25 in 1903. About 1905 or 1906 the Bear Creek deposit 
near the North Toe River and Penland was opened by C. J. Edgar 
Company and was later worked for 11 years by Harris Clay 
Company. Sometime previous to 1918 it was abandoned but was 
later reopened and is still being worked by the Carolina China 
Clay Company. In 1913 this deposit and one on Beaver Creek 
were the only ones operating in the district, though prospects 
were known in the Gusher Knob, Grassy Creek, Spruce Pine, 
Boonford, and Micaville areas. The large Sparks mine of the 
Harris Clay Company at Minpro was opened in 1914 and pro- 
duced until about 1938 when a new pit was opened about a 
thousand feet to the northeast. The Spruce Pine mine on the 
southeast edge of town, probably the largest clay excavation in 
the district, was opened in 1916 but is now abandoned. In 1918 
Bayley 26 reported eight active mines, only three of which were 
in Jackson and Haywood counties, the others being in the Spruce 
Pine district. Two of these were near Micaville, opened about 
1914 by Harris Clay Company and since then largely worked out. 
The small Flukens Hill deposit was opened early in 1919 and was 
worked for about two years. The Lunday deposit was being pre- 
pared for operations in 1920 and an improved plant was com- 
pleted here in 1936. This deposit was not being worked in June 
1942 but preparations for reopening it were in progress. The 
Grassy Creek deposits were being operated in 1936 but have 
subsequently been abandoned and the plant removed. The very 
large deposits at Brushy Creek were intensively prospected in 
the early 1930's and the modern plant of Kaolin, Incorporated, 
constructed, operations starting in May 1937. 

Deposits being operated in June 1942 included : 
Brushy Creek, by Kaolin, Incorporated 
New Minpro, by Harris Clay Company 
Bear Creek, by Carolina China Clay Company 
The production of kaolin in North Carolina during the last 
twenty years is tabulated below; data are from Mineral Re- 
sources of the United States (U. S. Geological Survey) and 
Minerals Yearbooks, (U. S. Bureau of Mines). The division of 
the total between the Spruce Pine district and that in the south- 
west part of the State is not known. In recent years, probably 

2 * Keith, Arthur, op. cit., 1905. 

28 Ries, Heinrich, op. cit. (Prof. Paper 11), 1903. 

28 Bayley, W. S., op. cit. (Bull. 29), p. 34. 



Spruce Pine District, North Carolina 



19 



since about 1922, the whole production has come from the Spruce 
Pine district. Figures for the total production of kaolin from 
North Carolina are not available. 




Fig. 1. — Plant of Kaolin, Incorporated, near Spruce 
Kaolin Produced in North Carolina 

Year Short tons 

1921 11,681 

1922 14,586 

1923 23,673 

1924 16,858 

1925 18,799 

1926 20,719 

1927 20,334 

1929 19,788 

1929 17,678 

1930 24,674 

1931 12,234 

1932 6,857 

1933 6,878 

1934 . 7,146 

1935 8,162 

1936 8,657 

1937 :: a 

1938 . a 

1939 11,308 

1940 14,602 

a Only three producers. Figures cannot be revealed. 



Pine, N. C. 

Value 

$188,825 

214,552 
369,398 

277,418 
309,833 
331,487 
327,638 
298,841 
282,672 
391,432 
195,596 
102,865 
102,714 
106,742 
118,972 
126,353 
a 
a 
165,896 
202.642 



20 Residual Kaolin Deposits of the 

GEOLOGIC SITUATION AND ORIGIN 
ROCK TYPES 

The residual kaolin deposits of the Spruce Pine district were 
formed by chemical weathering of feldspathic rocks. Surface 
water containing carbonic, organic and other acids percolated 
down through the rocks where conditions were favorable and 
converted the feldspar to kaolin. 

All of the rocks of the district are deeply weathered except on 
the steeper slopes where the loose products of weathering are 
removed by creep and rain wash about as fast as formed. Most 
of the rocks contain appreciable feldspar but only granite and 
pegmatite contain sufficient amounts to yield large proportions 
of clay not contaminated with objectionable impurities. Though 
many of the pegmatites are deeply decomposed, they are rela- 
tively small. Some deposits of this type have been worked in 
this district but all mining of them is now abandoned. Probably 
because of the analogy with the pegmatite-kaolins in south- 
western North Carolina and because of the coarseness of the 
Spruce Pine granite, the deposits near Spruce Pine have until 
recently been considered derived from pegmatite also. Watts 27 
did remark that the pegmatite at the Penland deposit was very 
fine-grained and not unlike a granite in texture. Hess and 
Hunter 28 have made it clear that the large deposits now being 
worked were formed from enormously larger granite ("alas- 
kite") bodies. The location of commercially important kaolin 
deposits in the district is thus primarily controlled by exposures 
of the granite. 

FRACTURES 

The depth to which kaolinization has penetrated appears to 
depend mainly on topographic conditions (see p. 22). Another 
factor of importance, but one difficult to evaluate, is the amount 
of fracturing of the granite. The area seems not to have been 
subjected to important compressive stress since the late Paleo- 
zoic intrusions but vertical movements have recurred. Though 
the granite is not much distorted, in places it is somewhat shat- 
tered and cut by minor faults. Irregular expansion cracks are 
common and in some places systematic joints are developed. 
These openings have undoubtedly aided kaolinization and help 
account for variations in its degree where the topographic situa- 
tions appear to be alike. 



27 Watts, A. S., op. cit., p 14S 

28 Hunter, C. E., op. cit., (1940) p. 100. 



Spruce Pine District, North Carolina 21 

Of similar effect, though different in origin, is the rude platy 
flow structure found in places, where similar orientation of mica 
flakes and small inclusions give the granite a rough foliation. 
These surfaces of easy parting have opened, allowing free access 
to ground water. 

INCLUSIONS 

Many inclusions of mica schist, injection gneiss, hornblende 
gneiss, and, less commonly, mica gneiss are encountered in the 
granite. Consequently all of the clay deposits are more or less 
interrupted by horses of "slate". Their number and size seriously 
impair the value of the deposit in places and always constitute 
a mining problem. They also are weathered and contain clay, 
but in addition have much quartz, opaque mica and limonite. If 
mixed with the kaolin they introduce objectionable impurities 
which are expensive or impossible to remove. Furthermore, iron 
oxide formed by weathering of the inclusions may spread into 
the surrounding kaolin and ruin large portions. 

OVERBURDEN 

The overburden on the kaolin deposits is of two kinds: 
residual soil and stream sediment. In general the first is found 
on those portions of the deposits which are at highest altitude 
and farthest from the major streams. 

The residual soil overlying the granite is a brown sandy clay, 
not very plastic, with flakes of clear muscovite up to a quarter 
of an inch across. Rough pieces of quartz are mixed throughout 
and lie on the surface. Pegmatitic zones yield larger flakes and 
sheets of muscovite and big boulders of gray quartz. The upper 
foot or so contains much organic matter. Minor amounts of 
partly decayed feldspar occur where kaolinization has not been 
deep. The brown limonite stain lessens with depth so that the 
overburden grades downward through light brown into uncon- 
taminated white sandy kaolin. The thickness of stained soil 
overburden is usually four to six, and seldom over ten, feet. 

Kaolin areas at lower altitudes and near the rivers generally 
have a capping of water-laid sediment, which is a portion of the 
strath or strath terrace. The bulk of the capping is unconsoli- 
dated brown silt and clay, with gravel and sand layers. In 
general the lower part contains much gravel, but the bottom may 
be gravel, sand or clay. The gravel pebbles usually are sub- 
rounded ; well-rounded ones are not common. Some boulders over 
a foot in diameter were observed but most are smaller. The 



22 Residual Kaolin Deposits 6f the 

clay layers are very plastic, in contrast to the residual soil de- 
rived from granite. The whole deposit is heavily stained with 
iron oxide and in part is cemented by it. Stratification is irreg- 
ular, with scour and fill, and cross bedding. The thickness ranges 
from a few feet to nearly thirty, and may vary rapidly laterally 
as both the upper and lower surfaces are irregular. The deposit 
thins out away from the streams as the strath surface rises, so 
that only the lower and central portions of the strath are now 
blanketed with sediment. 

TOPOGRAPHIC SITUATION 

The kaolin deposits thus far mined lie at low altitudes and 
near the rivers and roads. The reason is clear from plates 2 
and 4, where it can be seen that all deposits investigated lie 
within the areas of the low incised strath bordering the major 
streams. A tabulation of the altitudes of all the deposits showed 
the range to be from 2,500 to 3,000 feet, the great majority 
falling between 2,550 and 2,800 feet. Those along the upper 
reaches of the river are higher than those farther downstream, 
in agreement with the strath altitudes. The tops of the deposits 
range from 65 to 345 feet above the nearest stream. The bottoms 
extend down to the stream level, mainly where the stream flows 
at or near the strath level. Where the strath is deeply intrenched, 
as near Lunday, the bottom of the deposit may be as much as 200 
feet above the local drainage. 

The slope of the land surface over the deposits is gentle. Some 
deposits have nearly level tops, especially where capped with 
terrace sediment. Most, however, slope irregularly toward the 
streams with grades of about 6 to 25 percent (roughly 3% to 14 
•degrees). In a few places the slope is as steep as 40 percent 
(22 degrees) near the upper limits of the deposit, but on slopes 
as steep as this the clay is thin. 

The depth of kaolinization varies considerably from place to 
place, ranging from 10 or 20 feet to 60 or 70 feet. The old 
Sparks pit at Minpro has been reported mined in places to a 
depth of 135 feet below the surface. The average depth all over 
the various producing pits, however, would probably be not over 
about 40 feet. The lower limit of kaolinization must have been 
the local water table, and evidently its position during the time 
of strath erosion rather than its present position mainly de- 
termined the depth. This conclusion is drawn from the facts 
that at the Lunday deposit, where the South Toe River has 
trenched the strath in a deep gorge, the bottom of the deposit is 



Spruce Pine District, North Carolina 23 

about 200 feet above river level and 1,500 feet horizontally from 
it, whereas at the Brushy Creek deposit, where the North Toe 
River flows at strath level, the bottom is about 15 or 20 feet above 
river level and 2,000 feet distant. In the first instance several 
deep tributary valleys run so close to the deposit that circulation 
of ground water must be possible at lower levels than the bottom 
of kaolinization, while in the second case the two depths must 
practically coincide. Thus, most of the weathering responsible 
for the kaolin probably occurred during the long strath erosion 
period, though kaolinization has doubtless penetrated somewhat 
more deeply in the shorter time since rejuvenation. 

The strath has been considerably dissected since uplift stimu- 
lated erosion. In most places the main streams and the tribu- 
taries have cut into it, leaving flattish remnants between them. 
The resulting even-topped gently sloping ridges lying between 
the smaller tributaries (and underlain by granite) are typical 
locations for kaolin deposits. The flatter the top and the greater 
the area, the better the chance for a good deposit. The presence 
of a sedimentary capping indicates that no kaolin has been re- 
moved by erosion in post-strath time, but its absence is not a 
discouraging sign. 

COMPOSITION 

The Spruce Pine kaolins, being residual deposits, contain the 
resistant minerals of the granite plus its weathering products. 
The quartz is little affected, though sharp edges of grains may 
be blunted by solution. The muscovite remains fresh, though 
clay may penetrate the cleavage planes. The feldspar is more or 
less thoroughly, but seldom completely, altered to clay, so that 
partly decomposed grains and lumps remain. Under the con- 
ditions which prevailed, the plagioclase was more quickly and 
thoroughly attacked than the microcline. This is strikingly 
shown by many weathered perthite crystals where the plagioclase 
laminae have been altered and removed, leaving the hard potash 
spar in sharp relief. As a consequence, the "sand" which is 
removed in washing the kaolin contains more potash than soda 
spar, though the reverse is true in the granite. Since the pegma- 
titic zones commonly have a higher proportion of microcline than 
the normal granite, they may remain harder than the rest of the 
deposit. Muscovite-plagioclase pegmatites yield sheet mica and 
rich clay zones. Garnet crystals become specks and spots of 



24 Residual Kaolin Deposits of the 

limonite with fine stained mica or chlorite. This is one of the 
most objectionable impurities because almost impossible to re- 
move, and where abundant may ruin the deposit. 

When inclusions of mica schist and injection gneiss are mined 
with the koilin, quartz and coarse mica with little iron stain is 
introduced but this can be removed with little difficulty by 
washing. The less common mica gneiss inclusions may yield 
finer mica and an injurious amount of limonite. The worst in- 
clusions are those of hornblende gneiss, which weather to a fine- 
grained mixture of limonite and clay. This is almost impossible 
to remove by washing and such inclusions have to be carefully 
avoided in mining. Disseminated limonite stain, concentrated 
along and near fractures, is often found near hornblende gneiss 
inclusions and under terrace cappings. 

Though feldspar may constitute nearly three-fourths of the 
granite, the percentage of clay derived by weathering of this 
rock is never this great because of incomplete decomposition. In 
some deposits formed from pegmatite, a recovery of 40 percent 
or more has been made, but in those derived from granite a re- 
covery of 20 to 22 percent is high. In most cases the recoverable 
kaolin is appreciably less, 15 percent being common, and some 
deposits are operated on as little as 8 or 10 percent. Washing 
eliminates all impurities from the clay except a little of the 
finest mica and quartz. Two chemical analyses of washed kaolin, 
quoted from Hunter 29 and furnished by Harris Clay Company 
and Kaolin, Incorporated, of Spruce Pine, follow: 

Analyses of Washed Kaolin Samples 

No. 1 No. 2 

(%) (%) 

Si0 2 47.94 46.18 

A1 2 3 37.02 38.38 

Fe 2 3 0.60 0.57 

Ti0 2 :--~ 0.02 0.04 

CaO 0.30 0.37 

MgO 0.07 0.42 

K 2 1.25 0.58 

Na 2 0.06 0.10 

Zr0 2 -- 0.08 

Ignition loss - 13.03 13.28 



Total 100.29 100.00 



29 Hunter, C. E., op. cit., (1940). p. 102. 



Spruce Pine District, North Carolina 25 

These analyses are typical of the washed product obtainable. 
Published analyses show the following ranges in composition : 

Si0 2 45 to 49 percent 

A1 2 3 ; ,— - 36 to 40 percent 

Fe 2 3 (& FeO) 0.1 to 0.8 percent 

Ti0 2 Trace to 0.1 percent 

Any of the kaolins in the Spruce Pine district are reported 30 
capable of being washed to yield 37 percent or more A1 2 3 , and 
that even those too stained for ceramic use would not have over 
1*4 percent Feo0 3 . 

MINING AND PROCESSING 

The overburden is easily removed by drag-line scrapers or 
power shovels. The clay is mined in part by power shovels and 
loaded into trucks which carry it to the plant. At Kaolin, In- 
corporated, trucks, and a drag-line scraper, deliver the clay to 
a belt conveyor in the center of the pit, which transfers it to the 
top of the mill. Other deposits are mined hydraulically ; a 
water jet washes the clay and fine associated minerals to the 
bottom of the pit, where the slip is raised by bucket elevator to a 
flume running down to the plant. Some hand work with pick and 
shovel may be necessary to remove undesirable portions. Large 
inclusions are mined around and left standing, often precari- 
ously, while smaller ones are loaded separately and dumped with 
the overburden. It is suggested 31 that overhead cableways could 
be profitably constructed to bring clay from distant deposits to 
a central plant. 

The kaolin is separated from the associated minerals by a 
complex procedure involving grinding, washing, screening, sett- 
ling, and flotation. Details of modern methods are found in 
papers by Grout 32 33 , Trauffer 34 and Hubbell 33 . Recoveries usually 
range from 8 or 10 percent to 15 or 17 percent. An important 
byproduct is fine ground mica. Other possible products which 
are not now saved, are quartz and potash feldspar for ceramic 
purposes. 



30 Smith, F. E , Harris Clay Company, personal communication. 

31 Janatka, Richard, Kaolin, Incorporated, personal communication. 

32 Grout, J. R., Jr , Better china clay from improved benefication: Eng. and Min. Jour., 
vol 138, no. 7, pp. 341 and 352, July 1937. 

33 Grout, J. R., Jr., A new process North Carolina kaolin refinery: Am. Ceramic Soc. Bull., 
vol. 16, no. 10, pp. 387-390, October 1937. 

:w Trauffer, W. E., Processes kaolin by foreign method: Pit and Quarry, vol. 32. no. 6. 
pp. 41-44, December 1939. 

35 Hubbell, A. H., Mining and washing kaolin in western North Carolina: Eng. and Min. 
Jour., vol. 144, no. 1, pp. 51-53, 65, January 1943. 



26 Residual Kaolin Deposits of the 

RESERVES 
TOTALS FOR THE DISTRICT 

The amount of crude kaolin in Avery, Mitchell, and Yancey 
counties was estimated by Hunter 36 at 51 million tons. His 
figures 37 for each individual deposit are summarized in Appendix 
A. The finished kaolin available was estimated at about 4 1/2 
million tons. 

The estimates from the present investigation are given in the 
accompanying tables. Since some of the quantities involved 
could not be determined accurately by surface work and shallow 
borings, but depended in part on judgment, the tables include 
two sets of figures giving the probable and possible amounts. 
The "probable" figures are conservative but not minimum, the 
"possible" figures optimistic but not extreme. The amount of 
washed kaolin available in the four groups of deposits investi- 
gated is calculated to be between 3 and 7 million short tons. 

APPRAISAL OF DATA 

In order that the degree of reliability of the estimates may be 
appraised, the means of obtaining the data are explained and the 
sources and limits of error of each item evaluated below. 

Areas. — The areas underlain by clay were determined by sur- 
face observations and soil auger borings. This information was 
plotted on topographic maps (scale 1/24,000; contour interval 
50 feet) and limit lines drawn. These lines are doubtless in- 
correct in places but could be made truly accurate only by bor- 
ings spaced at intervals of 50 feet or less all over the areas. For 
the Brushy Creek deposits these lines were transferred to a 
larger scale (1/2,400) map (pi. 3). On this the sizes of the 
kaolinized areas were determined by drawing triangles and 
parallelograms within the limit lines, scaling their dimensions 
and calculating. For the other deposits the outlines of the areas 
were traced from the field maps onto quadrille paper (20 by 20 
lines per inch) and the number of included squares counted. In 
the cases of squares lying partly within the limit lines, those 
more than half inside were counted as wholes and those more 
than half out were omitted. The mean of horizontal and vertical 
counts was used. The errors in figuring the sizes are thought to 
be less than the inevitable errors in locating limit lines. 



36 Hunter, C. E., op. cit., (1940). p. 102. 

37 Communicated personally by Mr. Hunter, through the courtesy of Mr. H. S. Rankin, 
Regional Products Research Division, Commerce Department, Tennessee Valley Authority. 



Spruce Pine District, North Carolina 27 

Thicknesses. — Data on the thicknesses of kaolin available be- 
low the overburden are variable in their reliability. For much 
of the Brushy Creek area very good borehole logs were available. 
For deposits adjacent to active or abandoned clay workings good 
determinations could be made. Elsewhere exposures in mine and 
prospect drifts helped greatly. Soil auger borings in prospecting 
pits and gullied roads were deep enough to supply minimum data. 
Oral information from operators, workmen and others was con- 
sidered where it seemed dependable. In some places, however, 
reasonable guesses based on experience elsewhere had to be made 
from the topographic situation. Neither tops nor bottoms of the 
deposits are planes, so that a greater thickness of clay is en- 
countered in one part than in another. The values used are 
average for the whole producing area, less than may be expected 
in central and upper parts and more than near the margins. To 
determine the thickness with certainty would require systematic, 
closely spaced, deep drilling entirely through the deposits. Lack 
of certainty as to this quantity was the main reason for com- 
puting probable and possible amounts. The ranges given are 
reasonably sure to bracket the true thicknesses. 

Inclusions. — Data on the volume of the deposit occupied by 
inclusions were especially difficult to obtain. Where possible the 
inclusions were mapped and their areas excluded. In places 
where a good many boreholes had been put down rough calcu- 
lations were possible. Examination of active and worked out 
deposits was particularly useful. Because this amount depended 
so much on judgment it is expressed as a percentage. This de- 
duction amounts to a "factor of safety" to take care of unpre- 
dictable inclusions, large quartz veins, and hard slightly kaoli- 
nized areas. The less that was known about a deposit the higher 
this factor was set, and it probably runs high, for the entire 
district. 

Densities. — Samples of known volume were taken by using a 
section of heavy iron pipe (diameter 7 inches, length 5.8 inches) 
with one edge beveled. A smooth surface on the clay was 
leveled off and the pipe driven down till flush with the surface. 
The surrounding clay was dug away to the level of the pipe's 
lower edge and the enclosed clay bagged. The sample was 
weighed, moisture content determined, the dry weight and 
density computed. Seven determinations from varying situations 
in four deposits were made. They ranged from 69 to 85 and 
averaged 77 pounds per cubic foot. These figures are probably 



28 Residual Kaolin Deposits'of the 

slightly low because the jarring while driving the pipe loosened 
the clay somewhat. For deposits where determinations were not 
made, 80 pounds per cubic foot was used. The Harris Clay Com- 
pany uses 90 and Hunter and Mattocks used 85 pounds per cubic 
foot. 

Recoveries. — Information on the average recovery obtained 
from deposits which had been or were being worked was sup- 
plied by the operators. For others estimates were made by com- 
paring the clay with that of worked deposits. This item is 
thought to be pretty dependable. 

Most of the computations were made by slide rule and so are 
not exact. Their order of accuracy, however, is as high as that 
of the quantities concerned. 

DISTRIBUTION AND GROUPING 

Four groups of deposits in the Spruce Pine district were in- 
vestigated as possible sources of aluminum ore. Two of these, 
the Brushy Creek and Gusher Knob, are compact groups of 
deposits, each derived from a single granite mass. Both lie in 
western Avery county, mainly in the Linville Falls quadrangle 
but extending westward into the Spruce Pine quadrangle (pi. 2). 
The other two groups, Spruce Pine and Newdale-Lunday, include 
groups of deposits mostly derived from different granite bodies. 
Though scattered, they are close enough together to supply a 
centrally located plant. The Spruce Pine group lies in Mitchell 
county, in the south-central part of the Spruce Pine quadrangle 
(pi. 4). The Newdale-Lunday group lies in Yancey county near 
the center of the Micaville quadrangle (pi. 4). 

INDIVIDUAL DEPOSITS AND GROUPS 
BRUSHY CREEK GROUP 

The Brushy Creek deposits (pis. 2 and 3) were first worked in 
May 1937 by Kaolin, Incorporated, after extensive prospecting 
by boreholes and adits. By 1942 a pit on the western edge, about 
1.7 acres in area and up to 43 feet deep, had been excavated. 
The amount of kaolin produced must exceed 10,000 tons. 

The deposits fall into three subgroups. (1) The part lying 
adjacent to the active pit (pi. 3, areas 1-6 inclusive) is flat- 
topped and at a little over 2,700 feet altitude. Its overburden 
of terrace sediment ranges in thickness from 4 to 28 feet, aver- 
aging 16 feet. Kaolin up to 40 feet thick has been penetrated 
in places, though five boreholes encountered hard granite after 



Spruce Pine District, North Carolina 



29 



19 to 35 feet of clay. (2) The part to the northeast lying along 
Brushy Creek (areas 8-20, 30-32 inclusive) is uneven and steeper, 
reaching in places up to 3,000 feet altitude. The overburden 
here, except along the lower edges, is residual soil and stained 
kaolin, ranging from 2 to 25, and averaging about 6 feet in 
thickness. Over 60 feet of clay is known in places. Only a small 
section of Brushy Creek (areas 19 to 20) along the north side of 




Fig. 2. — Mine of Kaolin, Incorporated, near Spruce Pine, N. C. Note thick 
overburden of stratified gravel, sand, and clay in left background. 

Mill Ridge slopes gently enough for commercial clay. (3) On the 
south side of Mill Ridge toward Laurel Creek (areas 21-29) a 
maximum of 54 feet of kaolin has been determined. This sub- 
group is like the second in having rough, steeper slopes and 
being at higher altitude. The residual soil overburden in the 
part prospected averages 11 feet in depth. 

The kaolin of the Brushy Creek deposits is of good quality. 
Stain from garnets or from hornblende gneiss inclusions is rare. 
Hard potash spar and large quartz veins are abundant in the 
clay. The mill recovery averages 15 percent but samples have 
yielded up to 24 percent. The quantity of clay in the various 
areas of the deposits is given in Table 1. The total for the group 
is between 1V*> and 3 million tons of washed kaolin. 



30 



Residual Kaolin Deposits 6f the 



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Weight — Washed 
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coO^MDO-IOON-OOONI^-ONt— iOloOnloOOOO^gOOO 
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Recovery 
(percent) 


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Weight — Crude 
(short tons) 


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co O lo O O O 

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VON co Ol Ol ON 
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r-H t-h 


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OJ t— 1 oi-<+ico ^ON t"-~ -<f CONMrOrH O "^ 

T— 1 t— 1 t-H 


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Density 
(lbs. per 
cu. ft.) 


r^ r^ t^- r-^ r^- r-- 
r^- 1>. r^ t^ n r^ 


N- n- r^. r^. n o~ r-» o- r-» t^ t-^ t^. o- 1-^ t^- 1-~- 
r^ i^. r-~. n- t^ r^ t^ n- r-~ r-~ t-» r-- 1^. r-» r-~ t^ 


Inclusions 
(percent) 


CU 

CO 
CO 

O 
Oh 


lo O O O O O 


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(N tH t— It— It— 1 !— Ii— 1 T-H T-H T— It— 1 i-H t— It— 1 


CU 

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03 

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s- 

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Thickness 
(ft.) 


cu 

CO 
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\Q MD Tt< Tfl r^H CO 


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cu 

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03 

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■^ -^ CO CO CO O) 


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OJ-^i COMCN 0104 COCO CO CO O) CO CO coco 


Area 
(sq. ft.) 


231,000 
142,800 

392,725 

760,000 

1,120,000 

528,200 


(uncertain) 
154,000 
651,200 

792,000 
301,500 
247,500 

367,330 
677,980 

543,200 
293,440 

253,000 
540,500 
302,500 
280,000 
113,750 
31,32 
657,400 
281,200 


i- 

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Brushy Creek 
No. 1 
2 
Sum 1-2 

3 
4 
5 
6 
Sum 3-6 


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sees s 

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CO C/3 C/3 CO CO 



Spruce Pine District, North Carolina 



31 



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32 Residual Kaolin Deposits of the 

The Brushy Creek deposits are not near a railroad but lie just 
a few hundred yards from a concrete road (U. S. Highway No. 
19-E). The distance to the nearest shipping point on the rail- 
road, Spruce Pine, is five miles. The different deposits of the 
group are easily accessible to the present plant of Kaolin, In- 
corporated, now being operated by Harris Clay Company, except 
for areas 21-29 inclusive; a road or aerial cable way would have 
to be constructed to reach them. 

This deposit appears to be the largest and best in the district. 
A good deal of prospecting has been done in several parts of the 
area, though not all of the information obtained is now available 
or usable. The borings were in part haphazardly distributed and 
elsewhere not spaced closely enough. Some parts have not been 
bored at all and others not deep enough to make sure of the 
thickness. Enough work has been done, to justify belief that this 
deposit meets the requirements for aluminum ore. More definite 
information on the individual parts is desirable, especially those 
along upper Brushy Creek and along Laurel Creek. Completely 
reliable estimates of tonnage would require good logs of several 
hundred systematically distributed boreholes, spaced not over 50 
feet apart, and each penetrating to unaltered granite. 

GUSHER KNOB GROUP 

A number of promising kaolin-bearing areas lie southeast of 
Gusher Knob, extending from three-quarters of a mile to two 
miles east of Ingalls (pi. 2). Though clay prospects in this 
vicinity have been known for thirty years, no kaolin has yet been 
produced. The western part of the deposit was prospected in 
1936 by F. L. Hess 38 of the Bureau of Mines and C. E. Hunter 
of Tennessee Valley Authority. About 80 holes were bored and 
at least three shafts sunk. 

The deposits underlie gently sloping, broad-topped ridges on 
the northwest side of Threemile Creek. These ridges are the 
dissected remains of a sediment-capped stream terrace lying 
about a hundred feet above the flat creek bottom. The overburden 
of gravel, sand, and clay is only two or three feet thick at its 
lower edge. Farther up on the ridges it increases to more than 
six feet in thickness. The sediment cap thins out at still higher 
altitudes and comes to an end at about 2,900 feet. Above this 
altitude four or five feet of residual soil covers the clay. 



38 Notes on three shafts and about a dozen boreholes, with unlocated sections of the 
drilled area, were supplied by Mr. Hess. 



Spruce Pine District, North Carolina 



33 



w 

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03 
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Weight — Washed 
(short tons) 


V 

CO 

CO 

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O oo O O O O 

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>-o ci O <-" i ^C <^» 


CO 

o 

CN 

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OO OO «-0 r— i -rfi Lr) 

O X ^h r^ On i< 
O r^ r-i oo r-H o\ 


O 

OO 
r^ 

OO 
«-0 


Recovery 
(percent) 


CD 

CO 
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Oh 


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r-H i-H r— 1 r-H r-H r— 1 


CD 

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r-H r-H r-H r— I r-H r-H 


Weight — Crude 
(short tons) 


CU 

IS 

CO 
CO 

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Q 


o o o o o o 

O O O OO o 
O vO O O CN o - 

^ O OO ^ ON O 

r--- O ^ c^i u~, oo 
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f-^J r-H r-H 


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O O O O O O 
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WH(Nlf)H\0 


Density 
(lbs. per 
cu. ft.) 


OO O O O O 

OO OO OO OO OO OO 


Inclusions 
(percent) 


CO 
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IS 
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Thickness 
(ft.) 


CU 

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u ~> "H* TfH L/-, CO LO 


o 

Ih 

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f~, (N CS c^, (N f^i 


Area 
(sq. ft.) 


o o o o o o 
o o o o o o 
o o o o o o 

o o o o o o 

vO M U"- N N ui 

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6 i 





34 Residual Kaolin Deposits *of the 

The distribution of kaolinized granite was difficult to de- 
termine accurately because of the thickness and extent of the 
overburden. The limit lines drawn are consequently less certain 
than in most other localities. The western boundary may lie 
farther west than indicated and nearly all lines are subject to 
revision. The western half of the area seems to be underlain 
by a fair-sized granite body with some inclusions, whereas to the 
east dikes with intervening septa of gneiss and schist appear to 
prevail. Large supplies of kaolin are more certain in the western 
than the eastern parts. The amount of inclusions is proble- 
matical but apparently large. Information is most reliable on 
areas 1, 2, and 3 and least so on area 6. 

The clay is of good average quality, in part stained from horn- 
blende gneiss but not unduly so. Kaolinization has been 
thorough, so that recoveries of 15 to 18 or perhaps even 20 per- 
cent may be expected. The broad expanse of flat terrace favors 
a good depth of clay and 90 feet has been reported 39 in one place. 
Between 450,000 and 1,250,000 tons of refined kaolin are esti- 
mated to be available in the Gusher Knob deposits (Table 2). 

The deposits lie adjacent to a good asphalt road (North Caro- 
lina Highway No. 194) and eight miles from the railroad at 
Spruce Pine. 

The Gusher Knob deposits appear to be the second most favor- 
able ones in the district. While they probably would yield less 
total kaolin than the Spruce Pine group, they have the advantage 
of compact distribution. The topographic situation is especially 
favorable to deep and thorough kaolinization. The principal un- 
certainty lies in the areal extent and distribution of granite and 
pegmatite ; a large and systematic boring program is essential to 
determine these facts. 

SPRUCE PINE GROUP 

This dispersed group (pi. 4) includes deposits in four compact 
subgroups as well as several other possible small sources not 
carefully investigated. The total washed kaolin available (Table 
3) in the group is estimated to be between 700,000 and 1,600,000 
tons. Taken as a group, these deposits are large enough and 
close enough together to satisfy the aluminum ore requirements. 
Three kaolin plants are located in the area, the Harris Clay 
Company plants at Spruce Pine and at Minpro, and the Carolina 
China Clay Company plant half a mile east of Penland. 



39 Smitn, F. E., Harris Clay Company, Dersonal communication. 



Spruce Pine District, North Carolina 35 

Spruce Pine deposit. — Much of this deposit on the southeast 
edge of the village of Spruce Pine (pi. 4) has been mined out 
between 1916 and about 1936 by Harris Clay Company. Much 
clay remains, however, in two areas to the south of the old pits. 
The site was abandoned because the clay contained enough iron to 
spoil it for high-grade ceramic use. The amount of iron, how- 
ever, is less than the tolerance for aluminum ore. The over- 
burden is principally terrace sediment, up to about 12 feet thick 
in places. Iron stain has been carried downward by ground 
water from this cap, as well as developed from garnets and horn- 
blende gneiss inclusions. The depth of kaolinization is reported 
by Hunter and Mattocks 40 to extend below river level (85 feet) 
in places. Bayley 41 reports, however, that the material was too 
hard to mine below 85 feet. A thickness _of 58 feet of clay below 
the overburden was measured at the northwest side of the west 
pit and of 69 feet at the southwest corner of the long east pit. 
The total thickness may be somewhat greater as the pits are now 
in part filled with waste. The recovery of washed kaolin is low, 
about 10 or 12 percent. In the two sections of this deposit 
between 150,000 and 300,000 tons of washed kaolin remain. The 
deposit is readily accessible, as it lies within 300 yards of the 
railroad. Part of the old plant has been removed but the mica 
recovery portion is still in operation. 

Grassy Creek deposits. — The Grassy Creek deposits (pi. 4) lie 
about two miles south of Spruce Pine. Three good-sized pits 
have been mined by Harris Clay Company but have been aban- 
doned since 1936. A large area in this vicinity is underlain by 
granite, not only on the east side of Grassy Creek around the old 
pits but also up Silver Run and Graveyard Creek to the west. 
Superficially the prospects look good in this area but kaoliniza- 
tion has been neither deep nor thorough. The old pits expose 
fairly hard granite within 20 feet of the surface. In many places 
the clay is too hard to penetrate with a soil auger for more than 
four or five feet. Much partly decomposed feldspar is found in 
the soil. A large area on the north side of Graveyard Creek has 
big boulders of granite lying on the ground and several outcrops 
occur. The whole area doubtless contains a good deal of clay, 
probably 300,000 to 500,000 tons in the five sections outlined, 
but the yield would be low and the operation proportionately 
expensive. A large part of the clay is badly stained by decom- 
posed garnets. The overburden is mostly residual soil four to five 



^Hunter, C. E., and Mattocks, P. W., op. cit., p. 19. 

41 Bayley, W. S., op. cit. (Bull. 29), p. 95. 



36 



Residual Kaolin Deposits of the 



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Spruce Pine District, North Carolina 37 

feet deep, through gravelly sediment occurs near the center of the 
valley. A concrete road, North Carolina Highway No. 26, run- 
ning through the area makes it readily accessible. 

English Creek deposits. — The English Creek valley (pi. 4) a 
mile southwest of Spruce Pine is largely underlain by partly 
kaolinized granite. No clay has been produced here, though a 
part (section no. 1) has been prospected. The overburden is 
residual soil five or six feet deep. Large irregular inclusions 
are numerous. The quality of the clay appears to be good. Be- 
tween 180,000 and 400,000 tons of washed kaolin could be pro- 
duced from five sections in the area. U. S. Highway No. 19-E 
skirts the north edge of the productive area and fair dirt roads 
run near all parts. The distance to the railroad at Spruce Pine 
is about 11/2 miles. 

Bear Creek deposits. — The Bear Creek deposits (pi. 4) lie 
near the North Toe River east of Penland between Bear and 
Little Bear Creeks, and about 2^ miles northwest of Spruce 
Pine. Six large pits have been worked since 1905 or 1906 and 
two are now (1942) operated by Carolina China Clay Company. 
The west side has been worked out except for two small areas 
south of the long pit. The oval hill in the central portion has 
been prospected and found workable in most places. The over- 
burden is mainly residual soil one to ten feet deep. The thickness 
of clay is variable, being 60 feet in one pit and only 25 feet in 
another next to it. Inclusions mainly of hornblende gneiss, 
stained areas, quartz veins, and hard areas are numerous. Re- 
covery is low, in part 15 percent but mostly 8 or 10 percent. 
Between 140,000 and 320,000 tons of washed kaolin are esti- 
mated to lie in these deposits. The pits are within 200 to 300 
yards of the railroad and the present plants are beside the tracks. 
An asphalt road, North Carolina Highway No. 26 skirts the east 
and north sides. 

Miscellaneous deposits. — Several other deposits (pi. 4) are 
known near Spruce Pine but were not investigated in detail as 
the outlook for large quantities of kaolin was poor. 

The earliest workings in the Spruce Pine district were along 
upper Bear Creek near Bear Creek church. Some additional 
good clay remains here in several spots but no important tonnage. 

At Minpro a large pit is now being operated by Harris Clay 
Company. This was opened about 1938 and has been mined very 
rapidly to a depth of some 40 feet. The granite is quite hard at 
30 feet and in some places at less depth. Much quartz from peg- 



38 Residual Kaolin Deposits of the 

matites and hard microcline is encountered. The reserve of clay 
here is very small. Fifteen hundred feet to the north-northwest 
in the vicinity of an old pit some additional supply might be 
obtained. 

On the low ridges on both sides of Pine Branch and Sullins 
Creek, a mile and a half northwest of Spruce Pine, kaolinized 
granite is exposed at a number of places. The granite bodies are 
very irregular and the inclusions large and numerous. A number 
of small pits with low recoveries might be opened in this general 
vicinity. 

In the southern part of the town of Spruce Pine, underlying 
Harris High School and adjacent areas, much partly kaolinized 
granite is exposed. The area is too built up, however, to be a 
practicable source. 

Kaolin has also been produced up Beaver Creek, a mile and a 
half northeast of Spruce Pine, but important additional supplies 
here are unlikely. 

NEWDALE-DUNDAY GROUP 

The deposits in the Micaville quadrangle (pi. 4) are smaller 
and more scattered than elsewhere in the district. Four sub- 
groups were investigated and four other deposits were visited. 
The total quantity of kaolin (Table 4) in the group is estimated 
to be between 400,000 and 1,300,000 tons. This group is sub- 
marginal in respect to the requirements for aluminum ore. The 
Harris Clay Company plant at Lunday is in the area. 

Newdale deposits. — Five possible deposits, none of which has 
been developed, lie around Newdale in the south central part of 
the Micaville quadrangle (pi. 4). A great many mica pits and 
drifts in most of the area expose good clay. The depth of 
kaolinization in many places is shallow, so that the smaller ton- 
nage estimates are doubtless the more accurate. Inclusions, 
mostly of schist and injection gneiss, are numerous. The over- 
burden of residual soil and stained clay is seldom over six feet 
deep. The recovery should be low, probably 10-12 percent. The 
quantity of clay estimated to be available is between 300,000 and 
900,000 tons (Table 4). The deposits lie within 500 yards of 
U. S. Highway No. 19-E. The nearest point on the railroad is 
Boonford, 2i/ 2 miles north-northeast of Newdale, reached by a 
good dirt road, North Carolina Highway No. 80. 

Butler Gap deposits. — Three small areas northwest of Butler 
Gap (pi. 4) give indications of clay. The deposits lie a little 



Spruce Pine District, North Carolina 



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Residual Kaolin Deposits of the 

naif a mile southeast of the Newdale group and are reached 
fair dirt road, the upper end of which is in bad condition, 
ay has been produced here. The granite bodies are rela- 
small dikes. The lowest one, farthest northwest, appears 
well kaolinized. The other two have steeper slopes and 
in feldspar and granite in the soil, so the clay is probably 
•w. The overburden is residual soil three or four feet thick, 
sions are numerous. The clay is of average quality; be- 
i 20,000 and 50,000 tons (Table 4) might be produced. 

mford deposit. — A large lens of granite half a mile south- 
of Boonford (pi. 4) has been well kaolinized. No clay has 
produced here yet. The overburden is shallow (4-5 feet) 




Fig. 3. — Mine of Harris Clay Company near Lunday, N. C. 



ial soil. The clay appears to be of good quality. Between 
and 150,000 tons (Table 4) exists in the deposit. North 
ina Highway No. 80 passes close to the deposit. 

%day deposits. — Clay production near Lunday in the center 
! Micaville quadrangle (pi. 4) started about 1921. Hydraulic 
tg was employed at first, in the eastern part of the deposit, 
t five acres have been mined and approximately 50,000 tons 



Spruce Pine District, North Carolina 41 

of refined kaolin produced (Grout 4243 ). In 1936 a new process 
refinery was completed and excavations started adjoining the old 
pit on the west. The deposit was formed from several closely 
spaced and partly coalescing dikes and sills. Inclusions or divid- 
ing septa of hornblende gneiss are very numerous and some 
parts of the clay are iron stained. Pegmatitic streaks with hard 
microcline are common. The overburden is residual soil and 
stained clay from four to six feet thick. Between 30,000 and 
90,000 tons (Table 4) of washed clay is available along the 
margins of the present pit and in a hill 800 feet to the northeast 
(area 2). Many smaller dikes of granite and pegmatite occur 
in the vicinity but most are too small or too slightly kaolinized 
to be important. A lenticular dike 0.7 mile southwest of the pit 
(area 3) probably would yield 25,000 to 40,000 tons (Table 4). 
The main deposit is near the plant of the Harris Clay Company, 
part of which is a thousand feet from the pit and the rest half a 
mile away on the other side of the North Toe River beside the 
railroad. The deposit may be reached from Micaville, four miles 
south, by a fair dirt road. 

Miscellaneous deposits. — A number of smaller deposits in the 
Micaville quadrangle (pi. 4) would furnish some additional clay. 

Near the southeast corner of the quadrangle, where U. S. 
Highway No. 19-E crosses Crabtree Creek, two deposits are 
known. The Rice scrap mica plant is working a small deposit 
south of the road and west of the creek. This deposit includes 
much hornblende gneiss, is badly stained, and would have a low 
clay yield. Half a mile east on the other side of the creek and 
mostly north of the highway is an undeveloped deposit. In- 
clusions are large and numerous. A fairly important though 
distant additional supply may exist here. 

Three-quarters of a mile east of Micaville and just south of the 
main highway hydraulic mining of scrap mica is in progress. 
Clay considerably stained from hornblende gneiss inclusions is 
exposed at several places in the vicinity but only small amounts 
could be produced. 

Along Snow Creek in the northeast part of the quadrangle a 
small deposit is known. Bayley 44 estimated its reserves as about 
20,000 tons of refined kaolin. The small size of the deposit and 
its distance from the others make it of doubtful importance. 



42 Grout, J. R., Jr., op. cit., (July 1937.). 

43 Grout, J. E., Jr., op. cit., (October 1937.). 
« Bayley, W. S., op. cit., (Bull. 708), p. 63. 



42 Residual Kaolin Deposits of the 

SUMMARY AND CONCLUSIONS 

The investigation shows that the residual kaolin deposits of 
the Spruce Pine district constitute a potential source of alumi- 
num ore provided that a suitable process for extracting alumina 
from kaolin on a commercial basis is developed. These deposits 
lie nearly midway between the aluminum reduction plants at 
Badin, North Carolina, and at Alcoa, Tennessee, about 175 miles 
by railroad from each. Though by no means as large as many 
sedimentary clay deposits, nor as high in alumina content as 
some, washed kaolin from the Spruce Pine deposits meets the 
established specifications and averages 37 percent or more in 
A1 2 3 and under one percent Fe 2 3 . The depth of minable kaoli- 
nized granite is rarely as little as 15 feet and is frequently as 
much as 50 feet. The overburden is comparatively shallow, aver- 
aging between 5 and 10 feet, and is almost never as thick as the 
clay. Two groups of deposits will yield over a million tons of 
washed kaolin and two others may do so. 

The Brushy Creek deposits are much the largest and most 
favorable. Between IV2 and 3 million tons could be produced 
from a comparatively small area. A large and efficient washing 
plant is already operating. The distance to the railroad is five 
miles by a paved road. 

The Spruce Pine group is second in regard to tonnage avail- 
able, containing between 700,000 and 1,600,000 tons. The indi- 
vidual parts of this group, however, are separated from each 
other by from one to three miles, necessitating considerable haul- 
ing if worked from a central plant. All but one of the parts is 
less than a mile from the railroad. 

The Gusher Knob deposits, though smaller than the Spruce 
Pine group, have the advantage of being a compact group. They 
may possibly yield over a million tons but they are eight miles 
from the railroad. 

The Newdale-Lunday group is the lest favorable source. It 
may possibly yield a million tons but it is not likely to do so. The 
individual parts are so scattered that much hauling, in part over 
poor crooked roads, would be involved. The largest deposits are 
three miles from the railroad, though some smaller ones are 
nearer. 

The total refined kaolin available in the district is estimated 
to be between 3 and 7 million short tons. 



Spruce Pine District, North Carolina 43 

APPENDIX A 



ESTIMATES OF KAOLIN RESOURCES OF SPRUCE PINE DISTRICT, 

NORTH CAROLINA, MADE BY C. E. HUNTER AND P. W. MATTOCKS, 

REGIONAL PRODUCTS RESEARCH DIVISION, COMMERCE 

DEPARTMENT, TENNESSEE VALLEY AUTHORITY 

Crude Refined 

(short tons) (short tons) 

AVERY COUNTY 
Gusher Knob 

Area ? 

Depth ? 

Deductions ? 

Yield 15% -3,304,800 567,816 

Brushy Creek 

Area 3,000 by 2,000 feet 

Depth 60 feet 

Deductions 10% stained 

25% hard 
Yield.. -12% 10,200,000 1,224,000 

MITCHELL COUNTY 
Grassy Creek 

Area ? 

Depth ? 

Deductions ? 

Yield 10% 4,600,000 460,000 

Graveyard Creek 

Area 1,000 by 600 feet 

Depth 70 feet 

Deductions 25% (inclusions) 

10% (hard and stained) 

Yield 10% 1,205,875 120,587 

English Creek 

Area ? 

Depth .? 

Deductions ? 

Yield 11% 1,987,654 218,641 

Spruce Pine 

Area ? 

Depth ? 

Deductions ? 

Yield 12% 850,616 102,074 

Sullivans (probably Sullins) Branch 

Area ? 

Depth .? 

Deductions ? 

Yield 11% 108,561 11,941 



44 Residual Kaolin Deposits of the 

(short tons) (short tons) 

Crude Refined 

Little Bear Creek — Penland 

Area 2,000 by 1,000 feet 

Depth .....65 feet 

Deductions ? 

Yield 11% 3,633,750 399,712 

Ledger Group 

Area ? 

Depth ? 

Deductions ? 

Yield ? 323,000 ? 

Crabtree Creek (east side) 

Area 1,000 by 600 feet 

Depth 90 feet 

Deductions 20% (inclusions) 

Yield 14% 1,836,000 257,000 

YANCEY COUNTY 

Rice property at Crabtree Creek 

Area 1,800 by 500 feet 

Depth 50 feet 

Deductions Vs ( inclusions ) 

Yield ......9% 1,275,000 114,750 

Butler Gap 

Area 800 by 400 feet 

Depth 60 feet 

Deductions 25 % 

Yield 9% 612,000 55,080 

Mayberry property, ox South Toe 
River near Hall's Chapel 

Area 4,000 by 300 feet 

Depth 30 feet 

Deductions 25 % 

10% 

Yield 7% 1,032,750 72,292 

Newdale (northeast) 

Area 2,000 by 900 feet 

Depth . 70 feet 

Deductions 25 % 

Yield 12% 4,016,250 481,850 

Deneen property, Newdale (south) 

Area 2,300 by 400 feet 

Depth 60 feet 

Deductions 50% 

Yield 9% 1,251,200 112,608 

MlCAVILLE 

Area 1,800 by 400 feet 

Depth 65 feet 

Deductions ? 

Yield 10% 248,634 24,863 



Spruce Pine District, North Carolina 45 

BOONFORD 

Area ? 

Depth ? 

Deductions ? 

Yield 12% 1,518,000 182,160 

LUNDAY 

Area 200 by 600 feet 

Depth...... - 60 feet 

Deductions V 3 

Yield 10% 1,224,000 122,400 

Other smaller deposits are not included in this list 

TOTALS 39,228,090 4,518,774 

(All calculations used a density for the crude clay of 85 pounds per cubic foot.) 



I!